Dev wrote on Jan 8, 2014, 00:52:As I recall, GFWL was basically entirely optional in FO3, unless you got the DLC through it.

Even if you bought the DLC through GFWL, those were DRM free as well. You could move the files from wherever GFWL put them into the Fallout 3\Data directory and enable them with the launcher or a mod manager.